University of Melbourne researchers analysed the data of 1307 men and women following their release from seven prisons across the state and found more than a quarter of those made hospital contact within 18 months.

Centre for Mental Health Research fellow Jesse Young said the top three injuries recorded were assault, self-harm and mechanical force, such as crushing injuries from external forces such as machinery.

“We identified over half of the people released from prison either had mental health issues, substance abuse problems or both - that is really quite a high number of individuals,” he said.

“Of those, we saw one in five with both substance abuse problems and mental health illness...they had a rate of hospital admissions for injury that was over 12 times the rate we see in the general community.”

People subject to incarceration and youth detention in Australia are excluded from Medicare, the Pharmaceutical Benefits Scheme and NDIS as they receive in-prison health services provided by state or territories.

Once released, they are able to access Medicare but that transition can cause interruptions to medical treatment, Mr Young said.

“Prisoners in Australia are uniquely excluded from Medicare while they are in prison...they can reinstate that when they get released however there is the potential there to have...what we call discontinuity or a lack of continuous care just by the simple fact that they don’t have a Medicare card to access preventative services like going to a GP or getting the medication they need,” he said.

“Although we did not generate direct evidence on health outcomes due to the exclusion of prisoners from Medicare, timely access to Medicare-subsidised medications and primary care are likely key to ensuring continuous care during the transition from prison to the community.”

A Federal Department of Health spokesperson said a person's elibility did not cease when they entered prison.

"For example, prisoners on parole who choose to consult a medical practitioner outside of prison are able to access private medical services and claim Medicare rebates," the spokesperson said.

"If a released prisoner has lost or misplaced their Medicare card they can re-apply to the Department of Human Services for a new Medicare card in the same way that every other Australian citizen would seek a new Medicare card."

An Australian Medical Association spokesman said there was good evidence that prisoner engagement with community-based healthcare providers prior to release from custody increased the chances of ongoing treatment.

“There is now good evidence that early engagement with appropriate primary care after release from prison is associated with better engagement in mental health and substance abuse treatment and may reduce recidivism,” he said.

The research was published in The Lancet public health journal on Thursday.